77 lines
2.3 KiB
C
77 lines
2.3 KiB
C
#ifndef _M68KNOMMU_DELAY_H
|
|
#define _M68KNOMMU_DELAY_H
|
|
|
|
/*
|
|
* Copyright (C) 1994 Hamish Macdonald
|
|
* Copyright (C) 2004 Greg Ungerer <gerg@snapgear.com>
|
|
*/
|
|
|
|
#include <asm/param.h>
|
|
|
|
static inline void __delay(unsigned long loops)
|
|
{
|
|
#if defined(CONFIG_COLDFIRE)
|
|
/* The coldfire runs this loop at significantly different speeds
|
|
* depending upon long word alignment or not. We'll pad it to
|
|
* long word alignment which is the faster version.
|
|
* The 0x4a8e is of course a 'tstl %fp' instruction. This is better
|
|
* than using a NOP (0x4e71) instruction because it executes in one
|
|
* cycle not three and doesn't allow for an arbitary delay waiting
|
|
* for bus cycles to finish. Also fp/a6 isn't likely to cause a
|
|
* stall waiting for the register to become valid if such is added
|
|
* to the coldfire at some stage.
|
|
*/
|
|
__asm__ __volatile__ ( ".balignw 4, 0x4a8e\n\t"
|
|
"1: subql #1, %0\n\t"
|
|
"jcc 1b"
|
|
: "=d" (loops) : "0" (loops));
|
|
#else
|
|
__asm__ __volatile__ ( "1: subql #1, %0\n\t"
|
|
"jcc 1b"
|
|
: "=d" (loops) : "0" (loops));
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Ideally we use a 32*32->64 multiply to calculate the number of
|
|
* loop iterations, but the older standard 68k and ColdFire do not
|
|
* have this instruction. So for them we have a clsoe approximation
|
|
* loop using 32*32->32 multiplies only. This calculation based on
|
|
* the ARM version of delay.
|
|
*
|
|
* We want to implement:
|
|
*
|
|
* loops = (usecs * 0x10c6 * HZ * loops_per_jiffy) / 2^32
|
|
*/
|
|
|
|
#define HZSCALE (268435456 / (1000000/HZ))
|
|
|
|
extern unsigned long loops_per_jiffy;
|
|
|
|
static inline void _udelay(unsigned long usecs)
|
|
{
|
|
#if defined(CONFIG_M68328) || defined(CONFIG_M68EZ328) || \
|
|
defined(CONFIG_M68VZ328) || defined(CONFIG_M68360) || \
|
|
defined(CONFIG_COLDFIRE)
|
|
__delay((((usecs * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6);
|
|
#else
|
|
unsigned long tmp;
|
|
|
|
usecs *= 4295; /* 2**32 / 1000000 */
|
|
__asm__ ("mulul %2,%0:%1"
|
|
: "=d" (usecs), "=d" (tmp)
|
|
: "d" (usecs), "1" (loops_per_jiffy*HZ));
|
|
__delay(usecs);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Moved the udelay() function into library code, no longer inlined.
|
|
* I had to change the algorithm because we are overflowing now on
|
|
* the faster ColdFire parts. The code is a little bigger, so it makes
|
|
* sense to library it.
|
|
*/
|
|
extern void udelay(unsigned long usecs);
|
|
|
|
#endif /* defined(_M68KNOMMU_DELAY_H) */
|